Convert Unicode char to closest (most similar) char in ASCII

How do I to convert different Unicode characters to their closest ASCII equivalents? Like Ä -> A. I googled but didn't find any suitable solution. The trick Encoding.ASCII.GetBytes("Ä")[0] didn't work. (Result was ?).

I found that there is a class Encoder that has a Fallback property that is exactly for cases when char can't be converted, but implementations (EncoderReplacementFallback) are stupid and convert to ?.

Any ideas?

If it is just removing of the diacritical marks, then head to this answer:

static string RemoveDiacritics(string stIn) {
  string stFormD = stIn.Normalize(NormalizationForm.FormD);
  StringBuilder sb = new StringBuilder();

  for(int ich = 0; ich < stFormD.Length; ich++) {
    UnicodeCategory uc = CharUnicodeInfo.GetUnicodeCategory(stFormD[ich]);
    if(uc != UnicodeCategory.NonSpacingMark) {
      sb.Append(stFormD[ich]);
    }
  }

  return(sb.ToString().Normalize(NormalizationForm.FormC));
}